Year maximum value in 2004 = 100 2006 11.773523576 2007 13.6495097797 2008 11.3900913383 2009 14.3961491153 2010 15.9191253288 2011 14.8978858676 2012 13.9641176763 2013 14.1961989044 2014 14.7569002639 2015 12.8748402553 2016 14.4390592205 2017 9.6708023641 2018 9.4337220519 2019 8.9802116977 2020 8.6872746828 2021 8.3910750562